But then there is the gray area of through-the-door communication. This only applies to single person restrooms. You are in there on the toilet and someone rattles the knob (locked, hopefully). Clearly the bathroom is occupied.

Yet, why is it that some people feel the need to reply to your knob jiggle?

Common responses are:
Occupied!
I'll be right out!
Just a minute!

But what about:

It'll be a while!
Come back later!

It's always so damn cheerful and honestly when I'm the one in there I don't want to really admit that I'm in there by giving myself away with a jovial update on my status. And isn't the locked knob enough? How often is the door locked with no one inside?

A really brief, lazy Google search could not find any input from Miss Manners. But this blog brought up some interesting points. And at least I know there are two other people out there who are opposed to responding to a knob-jiggle.